Many of the personal care products, mortuary and veterinary products, protective wear garments, and medical care garments and products in use today are partially or wholly constructed of materials such as thermoplastic film materials and thermoplastic fibrous nonwoven materials. Examples of such products include, but are not limited to, medical and health care products such as surgical drapes, gowns and bandages, protective workwear garments such as coveralls and lab coats, and infant, child and adult personal care absorbent products such as diapers, training pants, disposable swimwear, incontinence garments and pads, sanitary napkins, wipes and the like. For these applications thermoplastic nonwoven fibrous webs and thermoplastic films provide tactile, comfort and aesthetic properties which can approach or even exceed those of products or garments made from traditional woven or knitted cloth materials.
Other nonwoven or film material properties may be desirable depending on end-use applications. For example, certain end-use applications such as liners for diapers and incontinence products and feminine hygiene products call for nonwovens which are highly wettable and will quickly allow liquids to pass through them. On the other hand, for applications such as protective fabrics, for instance medical products such as surgical fabrics for drapes and gowns, and fabrics for other protective garments, barrier properties are highly desirable. Further, surgical fabrics for drapes and gowns should have a high degree of repellency to low surface tension liquids such as alcohols, aldehydes, ketones and hydrophilic liquids, such as those containing surfactants, in order to more fully protect medical personnel. Repellency to low surface tension liquids is also highly desirable for protective garment fabrics such as lab coats or industrial protective workwear, for example.
In order to provide desired functional properties or characteristics to products, melt-processable additive treatments are known which may be introduced into a thermoplastic polymeric melt and thus be extruded along with the thermoplastic polymer during the process of forming films and fibers. However, the main desired function of many such melt-processable additives is to produce the desired characteristic at the surface of the films or fibers, and many melt-processable additives are relatively very expensive compared to the base polymers conventionally used as fiber- or film-forming thermoplastic resins. Because the melt-processable additive is distributed throughout the thermoplastic melt during the mixing, melting and extruding process, much of the melt-processable additive is essentially wasted, trapped deep within the fiber or film, distant from the surface of the fiber or film where it can act to fulfill its desired function.
Consequently, there remains a need for thermoplastic extruded articles having a greater or enhanced expression or segregation of the melt processable additive treatment at the surface of the extruded article.